Ultrasonic cleaning with kirmuss and loss of high frequency details.

I have cleaned thousands of records with my US setup. What I hear is a reduction in high frequency content - but it is the hf NOISE which is gone. Like the hf tizz which is characteristic of low quality capacitors or resistors.

The US cleaning thread has lots of such information, like the test which I did to detect US damage. I didn't find any.

Hemoncdoc, I always use ear protection near an US machine.

It might be subtly irritating to be around the US machine when it is in operation (via bone conduction and other ways we sense ultra high frequencies), but can your hearing be damaged by frequencies that are so far above the range of audibility?  The frequencies are an octave or more above 20kHz, are they not? It's an interesting question.

What I was trying to say to the issue of damaging LPs is that there are dozens of machines on the market.  They vary quite a bit as to the frequency at which they operate and to the energy imparted into the bath.  No manufacturer wants to be associated with a product that does damage, but human error can be a b**ch, so caution is merited, IMO.  A third factor that theoretically could contribute to a damaging effect and which is not under the control of the manufacturer is length of time in the bath.

I have the CleanerVinyl system. I like it. But if you are worried about high frequency noise from the ultrasonic machine damaging your hearing, then wear closed back headphones while you are near it. I might start doing that. 

@lewm

My Elmasonic is specced at < 105dB at 1 meter, with the cover on; that’s one hell of a lot of sound power in an enclosed space. And of course the cover is not on when cleaning vinyl.

It would depend on the middle ears’ being able to transmit US frequencies, something of which Tim Paravincini seems quite sure - he designs for it. I see no reason to doubt it - whether there are hair cells to vibrate at that frequency or not (and so initiate the sensation of hearing), the energy may still be there in the semi-circular canals, breaking hair cells and permanently damaging hearing.

So I use protection. Just in case.